History of engineering & technology 3D confined wall jet BSTEM model Bathy-supp CFD CFD–DEM coupling DEM FGP (flaring gate pier) Froude number Gaussian distribution HEC-RAS controller LES-VOF method Ningxia–Inner Mongolia PIV Sichuan province TOPSIS method Tarim Basin U-shaped channel Y-shaped confluence channel Yellow River abutment aerated flow air bubble chord length air bubble frequency air concentration application depth artificial ventilation automation of flow modeling backward-facing step best depth